By distributing the wearer's weight over a large surface area, snowshoes permit a person to travel over shifting media such as snow without sinking. A typical construction employs a perimeter frame closed by a web, with a central binding that attaches the snowshoe to the foot or shoe of the wearer. Because the purpose of the snowshoe is to distribute the wearer's weight over a broad area, snowshoes tend to be large. Often they are several feet in length and one or more feet in width.
Although the large size is desirable when the snowshoe is in use, it is prohibitive of carrying a snowshoe in reserve capacity. In situations when a person might have to walk across deep snow, having a snowshoe in reserve is vitally important. For example, sportsmen on snowmobiles travel to remote areas having snow many feet deep. If the snowmobile should have a breakdown in a remote area, it might be impossible for a human on foot to walk to safety across the deep snow without the aid of snowshoes, skis, or the like. Similarly, any other traveller or sportsman in a snow covered area might find it essential to have snowshoes, whether due to breakdown, accident, change in weather, or unexpected conditions.
To better enable snowshoes to be carried in vehicles, on horseback, or in packs, many schemes have been developed to collapse or fold snowshoes. These schemes envision that the rigid frame can be collapsed by dissembling or folding. Collapsing the web presents little problem, since it is flexible and might be formed of swings, straps, or fabric sheet that can be folded or rolled into a compact package. However, reassembling a snowshoe presents a greater challenge. The frame must be assembled in a manner that it will be rigid, and the web must be attached to the frame to withstand the pressures of walking. The reassembly should be fairly quick and simple since this step is performed in the outdoors, often in severe weather and while gloves or mittens must be worn. Finally, the assembled snowshoe should perform in an acceptable way, similar to non-collapsible snowshoes, with a pivotal motion between the foot and the snowshoe.
The following patents show the state of the art in collapsible snowshoes. U.S. Pat. No. 3,555,707 to Sharratt et al teaches a snowshoe frame that can be folded once to half its initial length. When the hinge is opened in reassembly, a sheath telescopes over the hinge to provide rigidity during use. The binding is secured to two cross members of the frame and does not pivot, although the user is permitted to lift his heel. The lack of a toe pivot would cause this snowshoe to be difficult to use.
U.S. Pat. No. 4,348,823 to Knapp et al teaches an oval snowshoe frame that disassembles into three sections, reducing its length by two-thirds. For reassembly, the sections plug together and are secured by spring pins. In addition, an elastic cord runs through the oval frame so that all sections are strung together in proper order when disassembled and held in tension when assembled. The shoe binding appears to be a simple strap or bungee that could allow pivotal motion with the user's foot, although the resulting pivotal action is unreliable.
U.S. Pat. No. 3,636,643 to Lundquist teaches a threesection snow shoe that assembles by plugging together the frame sections. The assembled sections are held together by tension, created by stretching the web between the respective front and rear sections and the center section. The binding is a soft toe piece attached to a cross member of the center section. This binding would allow pivotal motion, although the pivoting action would be unreliable.
U.S. Pat. No. 4,203,236 to Erickson et al provides a snowshoe with tubular frame that folds on both longitudinal and lateral axes. When unfolded, internal plugs are pushed through the tubular members and across certain hinge areas. Other hinges are held open by a spreader plate that attaches transversely. There is no particular provision for a shoe binding, and it appears this snowshoe would be difficult to use due to lack of adequate pivoting action with the user's shoe.
U.S. Pat. No. 4,041,621 to Anderson teaches a snowshoe that is assembled from front and rear sections formed of hollow tubing, joined by being telescoped over a central rod received in the open end of each. Cross members lock the structure by plugging transversely through the sides of the respective front or rear tubes and the rod. Snowshoe webbing is strung on the frame to complete the structure. This patent deals with a method of permanent manufacture and not with a collapsible snowshoe that would be assembled at the point of use. There is not particular provision to enable a shoe binding to pivot with respect to the frame.
U.S. Pat. No. 3,599,352 to Novak et al teaches a collapsible snow shoe in which the frame is formed from steel rods. The rear section unplugs from sockets carried on the front rods. In addition, a cross brace folds in scissors fashion to allow the frame to collapse along a longitudinal axis. The shoe binding is an elastic cord wrapped on the user's foot, which would result in unreliable pivoting action between the foot and the snowshoe.
U.S. Pat. No. 4,720,927 to Abegg teaches a collapsible snowshoe in which the frame is formed of tubing sections joined by plug and socket connections. The web in this snow shoe is a fabric bag that encases the frame to hold it together but permits disassembly when the frame is removed from the bag. A toe binding is secured to the web and permits pivotal motion between the user's foot and the web.
The scope of this patent art shows a variety of assembly techniques that attempt to create a strong, rigid frame in an easily assembled, collapsible snowshoe. Yet, none of the prior art examples appears to have met all of the needs for a practical, reliable, easily assembled frame and snowshoe. In particular, it would be desirable for the frame to form a rigid configuration without requiring failure-prone components such as spring pins, sliding plugs or sliding sheaths.
Similarly, it would be desirable for such a reserve snowshoe to be extremely reliable in its pivotal action between the user's foot and the frame or web. Little attention appears to have been spent on this issue, which can be especially relevant in a snowshoe whose design is compromised to allow collapse, storage, carrying, and reassembly.
Further, it would be desirable for a collapsible snowshoe to require minimum assembly, and little or no careful or detailed work, since such assembly may be taking place under adverse weather conditions or difficult surroundings.
To achieve the foregoing and other objects and in accordance with the purpose of the present invention, as embodied and broadly described herein, the collapsible snowshoe of this invention may comprise the following.